Adding Contribution Guidelines & Nix

.gitignore

@@ -27,4 +27,6 @@ testing/udo_test.py
 
 Simulation.md
 
-monkeytype.sqlite3
+monkeytype.sqlite3
+
+result

CONTRIBUTING.md

@@ -2,20 +2,32 @@
 
 :+1::tada: First off, thanks for taking the time to contribute! :tada::+1:
 
-The following is a set of guidelines for contributing to cadCAD. These are mostly guidelines, not rules. 
+The following is a set of guidelines for contributing to cadCAD. 
 Use your best judgment, and feel free to propose changes to this document in a pull request.
 
 ### Pull Requests:
 
 Pull Request (PR) presented as "->".
 
 General Template:
-fork/branch -> BlockScience/staging
+user/branch -> BlockScience/staging
 
 Contributing a new feature:
-fork/feature -> BlockScience/staging
+user/feature -> BlockScience/staging
 
 Contributing to an existing feature:
-fork/feature -> BlockScience/feature
+user/feature -> BlockScience/feature
+
+### General Advise for Forked Repositories: 
+1. `git pull fork master`
+2. `git checkout -b feature` (new feature)
+3. Apply your awesomeness! (Commit Often)
+4. `git push fork feature`
+5. Apply a merge strategy you're comfortable with. I suggest a merge path to `master` similar to what's above.
+6. Submit PR from `user:master` into `BlockScience:staging`
+7. PR is queued for review
+8. PR Reviewed (Update necessary if rejected)
+9. PR Approved (There may be circumstances delaying the merge.)
+10. Your contribution merged into next feature release on `BlockScience:master`
 
 Thanks! :heart:

README.md

@@ -33,6 +33,13 @@ python3 setup.py sdist bdist_wheel
 pip3 install dist/*.whl
 ```
 
+**Option C: Using [Nix](https://nixos.org/nix/)**
+1. Run `curl -L https://nixos.org/nix/install | sh` or install Nix via system package manager
+2. Run `nix-shell` to enter into a development environment, `nix-build` to build project from source, and `nix-env -if default.nix` to install
+
+The above steps will enter you into a Nix development environment, with all package requirements for development of and with cadCAD.
+
+This works with just about all Unix systems as well as MacOS, for pure reproducible builds that don't dirty your local environment.
 
 ## 2. Learn the basics
 **Tutorials:** available both as [Jupyter Notebooks](tutorials) 
@@ -46,5 +53,7 @@ Familiarize yourself with some system modelling concepts and cadCAD terminology.
 * [Policy Aggregation](documentation/Policy_Aggregation.md)
 * [System Model Parameter Sweep](documentation/System_Model_Parameter_Sweep.md)
 
-## 4. Connect
+## 4. [Contribution](CONTRIBUTING.md)
+
+## 5. Connect
 Find other cadCAD users at our [Discourse](https://community.cadcad.org/). We are a small but rapidly growing community.

default.nix

@@ -0,0 +1,45 @@
+{ pkgs ? import <nixpkgs> { }, stdenv ? pkgs.stdenv, fetchPypi ? pkgs.fetchPypi
+, pythonPkgs ? pkgs.python36Packages
+, buildPythonPackage ? pythonPkgs.buildPythonPackage }:
+
+buildPythonPackage rec {
+  pname = "cadCAD";
+  version = "0.4.15";
+
+  # Nix allows fetching the project source from different locations
+  #src = fetchPypi {
+  #  inherit pname version;
+  #  sha256 = "4f2a4d39e4ea601b9ab42b2db08b5918a9538c168cff1c6895ae26646f3d73b1";
+  #};
+  # src = builtins.fetchGit {
+  #   url = "git@github.com:BlockScience/cadCAD.git";
+  #   ref = "master";
+  # };
+  src = ./.;
+
+  # In future, when tests are introduced, this can be updated to 'true'
+  doCheck = false;
+
+  buildInputs = with pythonPkgs; [
+    wheel
+    pytest
+    parameterized
+  ];
+  checkInputs = [ ];
+  propagatedBuildInputs = with pythonPkgs; [
+    pandas
+    pathos
+    fn
+    funcy
+    tabulate
+  ];
+
+  meta = with stdenv.lib; {
+    description =
+      "Design, test and validate complex systems through simulation in Python";
+    homepage = "https://github.com/BlockScience/cadCAD";
+    license = licenses.mit;
+    # maintainers = with maintainers; [ benschza ];
+    platforms = platforms.unix;
+  };
+}

shell.nix

@@ -0,0 +1,4 @@
+with import <nixpkgs> { };
+
+(let cadCAD = pkgs.callPackage ./default.nix { inherit (pkgs) ; };
+in pkgs.python36.withPackages (ps: [ cadCAD ps.pandas ])).env